This disclosure relates to a method and fixture for non-destructively verifying performance of a coated part. Hard coatings are typically applied to external surfaces of parts to enhance wear resistance, erosion resistance, or other properties of the part. The hard coating may debit other properties of the part, such as fatigue performance under cyclical loading conditions.
Manufacturers, end-users, or the like may verify fatigue performance of coated parts. For instance, sample parts may be taken from a group of parts and fatigue tested as indication of whether the other parts in the group have a desired level of fatigue performance. One drawback of this methodology is that the tested parts are effectively destroyed in the testing process, which may add expense to the overall manufacturing process.
Another methodology involves indirectly estimating the fatigue performance from a measured property of sample parts or coupons representing sample parts. For instance, coating hardness, modulus of elasticity, or residual stress may be used individually or in combination to estimate a level of expected fatigue performance. The estimation may be based on prior-collected experimental data that establishes a correlation between these properties and fatigue performance. The drawback here is that these properties do not indicate the mechanical strength of the material deposited, but rather a consistency in the plating process which one would suppose would indicate a mechanical strength consistency. Additionally some of these test methods have complexities on their own in how a measurement is made. Additionally, there are questions as to whether these properties are reliable predictors of fatigue performance.
Conventional methodologies for verifying fatigue performance also lack flexibility for variations of the coated parts, such as coating thickness (e.g., different models, part numbers, etc.). For example, a particular hardness, modulus, and residual stress that corresponds to a desired fatigue performance for a coating having a given thickness may not correspond to the desired fatigue performance level if the coating has a different thickness. A new correlation between the coating of the different thickness and the fatigue performance would have to be experimentally established.